Diy Magnatone

[lowell]

Anyone built one? Not finding any kits and read that the varistors for the pitch shifting vibrato are obsolete. The more recent schematics of Magnatones show varistors but I'm not seeing part #s.

[hylaphone]

If you dare, there was a great discussion over at ampgarage about varistor substitutes:
The Amp Garage :: View topic - Varistor Characteristics for Magnatone Vibrato Circuits

I would love to know what current manufacture Magnatones are using..

[Diablo]

NOS varistors have been available from the fellow that builds Juke amps, on ebay he sells as Warbler Muse, around $25/varistor.
I also wonder if the new Magnatone amp company will ever make their new production varistors available to the garage amp builders. Perhaps they don't want any competition?

[guitician]

It looks like he just had a sale on them... Pair Magnatone Rare Varistors July Sizzler Sale 50 OFF Ends 7 31 Midnight | eBay

[R.G.]

The varistors on old Magnatones are unique. Modern varistors are not even similar. They had a broad, slow change in incremental resistance over about a 70-150V range. Modern varistors snap over suddenly.

The circuit in a Magnatone was the inspiration for me designing the tube-vibe - a tube-based univibe. The phase shift stage in a Magnatone is a tube-based version of the one in the univibe. It works on the variation of resistance to a small signal through the varistors with a change in the gross voltage across them.

It is entirely possible to retrofit the Magnatone circuit with LDRs with their resistance changed by variation in light on them. I've done it.

People with financial or emotional interests in Magnatones being unique will scream loud and long about it not being possible to do this, or it sounding different (and by implication, worse) but it's remarkably similar.

As with all tone issues, your mileage may vary, depending on how emotionally invested you are in one side or the other.

[soundmasterg]

There are lots of threads around from the one above to another on the Hoffman forum talking about The Warbler to others with similar stuff where they were talking about the Magnatone and substitutions like the LDR's for the varistors. I have some of the FR1039 varistors that Zack at Vibroworld was selling before he closed up shop over 10 years ago. These were a replacement for the original Magantone ones if needed and had similar specs. The attached pdf gives a lot of very useful info about the Magnatone circuit.

Greg